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检查Ip掩码
//package com.nowjava;/**来 自 n o w j a v a . c o m**/ public class Main { public static void main(String[] argv) throws Exception { String ip = "nowjava.com"; System.out.println(checkIpMask(ip)); } public static String checkIpMask(String ip) { String ipParts[] = ip.split("\\."); if (ipParts.length != 4) return "IP address must have 4 parts"; String message = checkIpMaskPart(ipParts[0]); if (message != null) return message; message = checkIpMaskPart(ipParts[1]); if (message != null) return message; message = checkIpMaskPart(ipParts[2]);/*时 代 J a v a - nowjava.com 提 供*/ if (message != null) return message; message = checkIpMaskPart(ipParts[3]); if (message != null) return message; else return null; } private static String checkIpMaskPart(String part) { int dash; if ("*".equals(part)) return null; dash = part.indexOf('-'); if (dash == -1) { int value = Integer.parseInt(part); if (value < 0 || value > 255) return (new StringBuilder()) .append("Value out of range in '").append(part) .append("'").toString(); //break MISSING_BLOCK_LABEL_219; } int from; from = Integer.parseInt(part.substring(0, dash)); if (from < 0 || from > 255) return (new StringBuilder()) .append("'From' value out of range in '").append(part) .append("'").toString(); int to; try { to = Integer.parseInt(part.substring(dash + 1)); if (to < 0 || to > 255) return (new StringBuilder()) .append("'To' value out of range in '") .append(part).append("'").toString(); } catch (NumberFormatException e) {